WEBVTT - Ep 192 New World Screwworm: Oh-oh here they come 0:00:00.160 --> 0:00:03.560 One screw worm infestation that goes unreported could erase the 0:00:03.600 --> 0:00:06.520 tremendous gains that have been made in the Southwest against 0:00:06.559 --> 0:00:11.360 this insidious, multimillion dollar pest. The screw worm eradication workers 0:00:11.400 --> 0:00:14.240 can protect the gains, but only if they know where 0:00:14.240 --> 0:00:17.880 the pest strikes. You can help. Stopping screw worms is 0:00:17.920 --> 0:00:20.919 your concern, especially if you own livestock or a dog 0:00:21.040 --> 0:00:23.600 or cat or any other pet. All of you can 0:00:23.640 --> 0:00:28.640 help by finding and reporting screw worm infestations. Examine your 0:00:28.640 --> 0:00:33.000 animals at every opportunity. Look for cuts, scratches, or other wounds. 0:00:34.000 --> 0:00:36.720 If you find a wound that contains insect eggs or lobby, 0:00:37.120 --> 0:00:39.920 take about a dozen worms and all eggs from the wound. 0:00:40.600 --> 0:00:44.360 After you've taken the samples, treat the womb with approved insecticides. 0:00:45.040 --> 0:00:48.560 Place the samples in a container or jar in alcohol 0:00:48.800 --> 0:00:53.239 or water. At this point, speed is important. Call your 0:00:53.360 --> 0:00:56.440 county agent. He'll tell you where to send the samples. 0:00:56.520 --> 0:01:01.080 He'll tell you what action to take. Positive identification will 0:01:01.120 --> 0:01:05.560 be made by experts and measures taken to eliminate the parasite. 0:01:05.680 --> 0:01:09.720 A screworm infestation confirmed by positive identification sets off a 0:01:09.760 --> 0:01:15.760 series of emergency activities at schuwirm Eradication Headquarters, Admission, Texas. Here, 0:01:15.880 --> 0:01:18.920 millions of screworm flies are being read each day and 0:01:19.000 --> 0:01:23.320 made sexually sterile by exposure to gamma rays from radioactive cobalt. 0:01:24.160 --> 0:01:27.880 Released in special patterns and in large numbers, these laboratory 0:01:27.920 --> 0:01:31.600 reared flies fight for us against an outbreak. These sterol 0:01:31.640 --> 0:01:36.000 screworm flies mate with native flies, which in turn cannot reproduce. 0:01:36.920 --> 0:01:41.360 Release of steril flies, combined with intensive livestock inspection and 0:01:41.520 --> 0:01:46.760 use of insecticidal treatments, has already stemmed outbreaks. This new 0:01:46.840 --> 0:01:52.240 technique for insect control is eliminating screw worms from the Southwest. 0:01:52.520 --> 0:02:03.520 Complete success depends on quick discovery, quick reporting, quick action. Remember, examine, collect, treat, 0:02:04.200 --> 0:02:07.440 call you a county agent, and help stop schoolworms. 0:02:54.160 --> 0:02:55.440 That's the whole episode, is it not. 0:02:55.919 --> 0:02:57.120 Isn't that amazing? 0:02:58.440 --> 0:02:59.920 It's so comprehensive. 0:03:00.160 --> 0:03:06.079 It's so comprehensive. I okay, So that was from I 0:03:06.200 --> 0:03:10.440 found that on the USDA National Agricultural Library and like 0:03:10.520 --> 0:03:15.440 the screw worm exhibit, and it was a video produced 0:03:15.480 --> 0:03:19.360 in nineteen sixty three and it's called Lookout for screw Worms, 0:03:19.400 --> 0:03:24.160 and I just it was I think I didn't realize 0:03:24.400 --> 0:03:28.000 the extent to which screwworm was such a big deal 0:03:29.000 --> 0:03:32.960 during that time period for decades and decades and decades, 0:03:33.440 --> 0:03:37.360 enough so that there are like promotional videos like this, right, Okay. 0:03:37.280 --> 0:03:40.000 I'm really excited, Aaron to hear you talk about the 0:03:40.080 --> 0:03:42.680 history because I was reading and didn't realize like a 0:03:42.720 --> 0:03:46.480 lot of the history of like ranching the US was 0:03:46.560 --> 0:03:48.120 driven by screwworm. 0:03:48.360 --> 0:03:52.400 Yeah, I know, I know, And it's so funny. Yeah, 0:03:52.600 --> 0:03:54.640 I mean, there's there's so much to cover. We'll get 0:03:54.640 --> 0:03:56.960 into it. Okay, I want to start right now, but 0:03:57.680 --> 0:04:01.960 I want you to we'll start instead with introductions. Hi, 0:04:02.080 --> 0:04:04.080 I'm Aaron Welsh. 0:04:03.400 --> 0:04:04.320 And I'm Erin Almann. 0:04:04.400 --> 0:04:04.680 Update. 0:04:05.080 --> 0:04:06.880 This is this podcast will kill You. 0:04:07.560 --> 0:04:09.480 And today we're talking about screw worms. 0:04:09.840 --> 0:04:13.960 Shrew worms specifically for me, I'm talking about New World screwworm. 0:04:14.320 --> 0:04:17.760 Yeah. Well, we'll go over both different types of screwworms, 0:04:17.800 --> 0:04:21.159 new World and Old World, but realistically we're mostly talking 0:04:21.160 --> 0:04:22.799 about New World screwworm. 0:04:22.360 --> 0:04:26.480 Today, the one that's been in the headlines, in the news, 0:04:26.640 --> 0:04:29.880 spend in the news big time. It's gonna be a 0:04:29.920 --> 0:04:33.039 really interesting episode and a little bit maybe creepy Crawley 0:04:33.680 --> 0:04:36.479 as told to me A little bit, a very very 0:04:36.520 --> 0:04:39.839 creepy crawling. Yeah. Some of the descriptions I have are 0:04:40.760 --> 0:04:41.719 hard to stomach. 0:04:42.240 --> 0:04:44.560 Okay, that's good. I don't have that many of those. 0:04:44.720 --> 0:04:48.960 Okay, okay, I'm keeping it basic. But before we get 0:04:48.960 --> 0:04:53.360 into all of that, it is quarantine quarantiny time. Yeah, 0:04:53.400 --> 0:04:54.640 what are we drinking this week? 0:04:54.960 --> 0:04:59.080 We're drinking there's creworm driver. Yeah, it was just a screwdriver. 0:04:59.240 --> 0:05:03.039 Screwdriver which is, you know, vodka and orange juice, and 0:05:03.640 --> 0:05:06.040 with the addition of a gummy worm. 0:05:05.839 --> 0:05:11.080 Gummy worm to represent screw worm. We're getting real creative 0:05:11.120 --> 0:05:15.360 with these erin you know. I think that's okay, It's 0:05:15.440 --> 0:05:20.760 totally fine. Okay, it has to be. It has to be. 0:05:20.880 --> 0:05:22.119 We can do nothing else. 0:05:22.360 --> 0:05:24.320 Yeah, yeah, yeah. 0:05:24.360 --> 0:05:27.400 We'll post on the places that you can find it, 0:05:27.440 --> 0:05:29.839 like our website. This podcast will kill you dot com someday, 0:05:30.040 --> 0:05:32.920 but also definitely on our socials. This podcast will kill 0:05:32.960 --> 0:05:34.440 you what socials? 0:05:34.680 --> 0:05:36.920 Oh I have I try to post one. I don't 0:05:36.960 --> 0:05:38.800 know if it works very well. I can't figure out 0:05:38.839 --> 0:05:41.120 the dimensions, but hey, we're working on it. There's no 0:05:41.160 --> 0:05:41.520 way to do. 0:05:41.640 --> 0:05:44.440 Listen, there's a way. There's a lot of other great 0:05:44.440 --> 0:05:45.560 stuff on our website. 0:05:45.839 --> 0:05:48.960 Yes, there is. If we've got transcripts, We've got references 0:05:48.960 --> 0:05:50.680 for all of our episodes, so if you want to 0:05:50.720 --> 0:05:53.240 read more about screwworm, that's a great place to go. 0:05:53.800 --> 0:05:56.919 We've got links to merch to our bookshop dot org 0:05:57.000 --> 0:06:00.680 affiliate account, to our Goodreads list, to music by Bloodmobile, 0:06:00.920 --> 0:06:05.400 contact us, form a, submit your first hand account, form Patreon, 0:06:06.320 --> 0:06:08.120 other things. Probably check it out. 0:06:08.160 --> 0:06:11.760 There's a lot there. Yes, podcastwikill you dot com. If 0:06:11.760 --> 0:06:13.919 you haven't yet radio reviewed and subscribe, please do that. 0:06:13.960 --> 0:06:16.680 We'd really love it. We're on YouTube on the exactly 0:06:16.720 --> 0:06:19.480 Right network channel, and we're on all of your favorite 0:06:19.480 --> 0:06:25.000 podcasters including iHeartRadio, Apple Podcasts, Spotify, the like, the moving on, 0:06:25.480 --> 0:06:26.000 moving on? 0:06:27.800 --> 0:06:29.600 Are we done? Should we be great? 0:06:29.680 --> 0:06:30.200 You ready? 0:06:30.360 --> 0:06:30.560 Yeah? 0:06:30.680 --> 0:06:31.000 I am. 0:06:31.279 --> 0:06:33.440 I'm going to tell you about the biology of screwworm 0:06:33.960 --> 0:06:36.119 really fast, so that you can tell me about the history. 0:06:36.320 --> 0:06:38.640 Okay, okay, let's take a quick break and then we'll 0:06:38.640 --> 0:06:39.120 get to it. 0:07:12.200 --> 0:07:16.160 The star of today's show is the screw worm, which 0:07:16.200 --> 0:07:21.560 is a larval form of a fly. Most people, when 0:07:21.560 --> 0:07:25.440 we say screwworm mean the New World screwworm, which is 0:07:25.520 --> 0:07:35.360 the species Cochlio maya Homnivorax. Might have pronounced that wrong, hominivoras. Listen, 0:07:36.760 --> 0:07:39.560 it's the New World screwworm. But there is another one, 0:07:39.680 --> 0:07:46.360 the Old World screwworm, which is a species called Chrysoma besiana. Okay, 0:07:46.800 --> 0:07:51.200 and these are two different genera of fly, but both 0:07:51.240 --> 0:07:56.760 of them are blowflies overall not entirely dissimilar to the 0:07:56.760 --> 0:08:00.720 flies whose larval forms not that long ago an episode 0:08:00.760 --> 0:08:03.920 we hailed for the benefits of their ability to help 0:08:04.080 --> 0:08:04.960 heal wounds. 0:08:05.280 --> 0:08:07.400 Yeah, this may change our feelings on maggots. 0:08:07.400 --> 0:08:10.920 I think it will, because today we're talking about pretty 0:08:10.960 --> 0:08:16.800 much the exact opposite. Unlike most other species of blowfly, 0:08:17.360 --> 0:08:21.320 the New World and the Old World, screw worms larval 0:08:21.440 --> 0:08:27.640 forms feed not on necrotic or dead tissue, but instead 0:08:27.720 --> 0:08:33.480 on the warm and living tissue of warm blooded animals. Yeah. So, 0:08:33.559 --> 0:08:36.880 screwworms are a type of fly who lay their eggs 0:08:37.240 --> 0:08:40.360 in the flesh of living mammals in a way that 0:08:40.480 --> 0:08:43.000 causes really significant harm. 0:08:43.559 --> 0:08:48.120 Kind of like botflies, but more harmful, way more harmful. 0:08:49.760 --> 0:08:51.960 That So, what I want to do in this part 0:08:52.000 --> 0:08:53.960 of the episode is really just kind of take us through, 0:08:54.000 --> 0:08:57.320 like what are these flies? What do their life cycles 0:08:57.320 --> 0:08:59.760 look like? And why do they cause as much damage 0:08:59.800 --> 0:09:02.880 as they cause? So that you can tell us about 0:09:03.000 --> 0:09:04.719 all of the history with them, because I know it's 0:09:04.760 --> 0:09:10.280 really interesting. So adult flies of these both of these species, 0:09:10.320 --> 0:09:12.160 they look fairly similar. Most of what I'm going to 0:09:12.200 --> 0:09:16.559 talk about is about Cochliomaya, Hominivorax or the New World 0:09:16.600 --> 0:09:19.400 screw worm, but it mostly all applies to the Old 0:09:19.440 --> 0:09:21.720 World screwworm as well. They look a tiny bit different, 0:09:21.720 --> 0:09:23.280 but otherwise they're really quite similar. 0:09:24.200 --> 0:09:26.640 I'm so interested in their evolutionary history, which I didn't 0:09:26.679 --> 0:09:29.920 look up, like the relationship between them, was it like independent? 0:09:30.040 --> 0:09:30.280 Yeah? 0:09:30.360 --> 0:09:33.240 Anyway, Like oh, I didn't look at it either, but 0:09:33.240 --> 0:09:36.120 that's really interesting, Like yeah, how they both end up 0:09:36.160 --> 0:09:38.480 evolving this way of life that's so different from all 0:09:38.520 --> 0:09:40.680 of their other brethren, right. 0:09:40.640 --> 0:09:42.480 I mean it's a it's a great you know open 0:09:42.559 --> 0:09:45.280 niche I guess, like, yeah, someone else has got all 0:09:45.320 --> 0:09:47.640 the dead ones. You can get the live ones right 0:09:47.679 --> 0:09:50.080 exactly anyway. 0:09:49.720 --> 0:09:53.040 And so the adult flies, all entomologists everywhere are going 0:09:53.080 --> 0:09:56.000 to kill me for saying this. They look like a fly, Okay, 0:09:56.679 --> 0:10:02.040 how big, a little bit larger than a horse housefly. Okay, 0:10:02.320 --> 0:10:05.920 not a horsefly, housefly. And that's literally what they look 0:10:05.960 --> 0:10:08.319 like because they are blowflies. A lot of the houseflies 0:10:08.360 --> 0:10:10.880 that we see not houseflies, aren't necessarily blowflies. But you 0:10:10.920 --> 0:10:14.160 see these around. They've got almost like a metallic ish 0:10:14.400 --> 0:10:18.560 kind of bluish greenish body like most blowflies do. They 0:10:18.559 --> 0:10:21.840 have these big, giant orangish eyes across their heads, and 0:10:21.880 --> 0:10:24.520 then they have these three black and gray stripes along 0:10:24.559 --> 0:10:27.080 their back. The Old World screw worm has two of 0:10:27.120 --> 0:10:27.760 those stripes. 0:10:27.920 --> 0:10:28.240 Okay. 0:10:29.320 --> 0:10:32.640 The New World screw worms are native to essentially the 0:10:32.800 --> 0:10:38.120 entirety of the Americas, though they are primarily a tropical species. 0:10:38.160 --> 0:10:42.440 They need warm, moist soils in order to complete their 0:10:42.480 --> 0:10:48.320 life cycle, which goes something like this. The adult flies 0:10:48.480 --> 0:10:52.960 emerge from the soil where they pew paint, and it 0:10:53.040 --> 0:10:56.880 is only the adult females, As is usual for flies 0:10:57.240 --> 0:11:02.040 who cause the majority of the problems, they mate just 0:11:02.200 --> 0:11:07.160 one time. This is important, usually around day three to 0:11:07.280 --> 0:11:10.600 five of life, and then they start laying eggs right 0:11:10.640 --> 0:11:13.960 around that time day five to seven, after they come 0:11:14.000 --> 0:11:20.000 out of their people form, these flies lay two hundred 0:11:20.120 --> 0:11:23.320 to three hundred eggs. Some estimates say as much as 0:11:23.320 --> 0:11:27.360 five hundred eggs per clutch. It keeps getting worse, yep, 0:11:27.960 --> 0:11:32.640 because they lay additional clutches every three to seven days, 0:11:32.840 --> 0:11:36.480 for up to eleven clutches of two to three hundred 0:11:36.520 --> 0:11:39.280 eggs in a lifetime. And we can air in mathis 0:11:39.320 --> 0:11:41.079 though we don't have to because it's all over the papers. 0:11:41.360 --> 0:11:46.040 They lay a maximum of three thousand eggs per single 0:11:46.480 --> 0:11:50.600 female screwworm fly throughout the course of their twenty plus 0:11:50.760 --> 0:11:52.720 day adult life. 0:11:53.200 --> 0:11:56.520 I mean that is some hard work, it really is. 0:11:57.800 --> 0:12:01.360 They also often leave each one of their clutches in 0:12:01.480 --> 0:12:06.480 like several different egg masses, so not all like two 0:12:06.600 --> 0:12:09.319 hundred and one spot. They'll lay them like over of 0:12:09.360 --> 0:12:11.240 course of a few minutes or a couple of hours, 0:12:11.240 --> 0:12:12.280 in multiple times. 0:12:12.520 --> 0:12:14.960 Right, don't put all your eggs in one lesion. Kind 0:12:14.960 --> 0:12:19.600 of a mentality, exactly exactly, And they do. They lay 0:12:19.640 --> 0:12:24.720 their eggs in lesions on the margins of wounds on 0:12:24.960 --> 0:12:28.760 warm blooded animals, mammals, possibly birds, though they don't tend 0:12:28.800 --> 0:12:33.440 to prefer birds, but they can but all mammals, and 0:12:33.520 --> 0:12:37.720 they tend to prefer the kind of drier margins of 0:12:38.200 --> 0:12:43.199 fresh or bloody wounds compared to wounds that are severely 0:12:43.400 --> 0:12:47.400 infected or really wet or have a lot of like 0:12:47.520 --> 0:12:52.120 bacterial purulence. They want the freshest of flesh. 0:12:52.080 --> 0:12:56.040 The freshest of flesh, and they especially prefer wounds that 0:12:56.120 --> 0:13:01.040 have already been infested with screwworms, kind of like a 0:13:01.120 --> 0:13:03.680 signal that gets sent out like, hey, this is a 0:13:03.720 --> 0:13:08.680 really great wound, go ahead and lay your eggs here. However, 0:13:08.840 --> 0:13:12.719 they can also lay their eggs on other easily accessible 0:13:12.760 --> 0:13:16.959 parts of our like thin skin or mucous membranes, so say, 0:13:17.160 --> 0:13:23.560 the corners of eyes, or in noses yep, or near 0:13:23.640 --> 0:13:29.559 the perineum, or especially in places like insaane newborn mammals 0:13:29.600 --> 0:13:33.320 like newborn cattle or goats or horses that have an 0:13:33.400 --> 0:13:37.440 umbilical you know, stump that's not fully healed. That's a 0:13:37.440 --> 0:13:38.360 really common spot. 0:13:38.679 --> 0:13:39.959 Yeah. 0:13:40.040 --> 0:13:43.120 And then after a day or so, these eggs hatch 0:13:43.559 --> 0:13:48.720 into hundreds of maggots, the larval form of a fly, 0:13:50.200 --> 0:13:56.319 and these maggots eat their way in around and under 0:13:56.720 --> 0:14:01.920 the skin of their host, literally bear trying themselves in 0:14:01.960 --> 0:14:06.200 the process, which is how they get their name screwworm. 0:14:07.280 --> 0:14:12.079 Their wriggly little maggot bodies are even grosser looking than 0:14:12.120 --> 0:14:16.280 most maggots they have. It's not a thing. 0:14:16.280 --> 0:14:19.680 I mean that is a high bar. Maggots are disgusting looking. 0:14:19.960 --> 0:14:24.960 Maggots are gross looking. But these ones have particularly sharp 0:14:25.160 --> 0:14:30.920 hooks eyes of their mouthpieces, and their bodies have these 0:14:31.040 --> 0:14:34.960 sets of rings that kind of point backwards of these spines, 0:14:35.000 --> 0:14:37.360 these rings of like you know, like the kind of 0:14:37.400 --> 0:14:39.360 spines where like you can drive over them, but don't 0:14:39.400 --> 0:14:40.040 drive backwards. 0:14:40.160 --> 0:14:40.800 Yep. 0:14:41.160 --> 0:14:44.160 Yeah, and that is what helps them literally cork screw 0:14:44.200 --> 0:14:48.080 their way deep into the living tissues on which they're feeding. 0:14:50.240 --> 0:14:53.120 How big do these larvae get? 0:14:53.520 --> 0:14:55.440 Oh, that's a really good question. I actually didn't see 0:14:55.440 --> 0:14:58.160 anything about the particular sizes. I mean, they're not large. 0:14:58.160 --> 0:15:03.880 They're small individually, maybe a few millimeters big. Okay, okay, 0:15:03.920 --> 0:15:10.160 can Yeah. They feed for about a week before dropping 0:15:10.240 --> 0:15:14.080 off to pupate in the soil for another week, and 0:15:14.120 --> 0:15:15.760 then they'll emerge as adult flies. 0:15:17.560 --> 0:15:20.800 And once they emerge, okay, so I'm thinking about like 0:15:21.560 --> 0:15:26.480 going to in a place where screwworm is present. How 0:15:26.600 --> 0:15:29.920 many you said that the females only mate once, and 0:15:30.000 --> 0:15:34.440 so how many rounds of females in a year is happening, 0:15:34.480 --> 0:15:38.000 you know what I mean, Like, right, it's not like idea, 0:15:38.120 --> 0:15:40.920 it's like one week then do they overwinter, et cetera, 0:15:41.000 --> 0:15:41.560 that kind of thing. 0:15:41.680 --> 0:15:41.840 Yeah. 0:15:41.880 --> 0:15:43.800 So, I mean they tend to live in the tropics, 0:15:43.840 --> 0:15:46.080 and in the tropics, they're there all year round, right, 0:15:46.120 --> 0:15:49.240 and so they're going to be continually in each female. 0:15:49.560 --> 0:15:53.880 Adult females live for about twenty ish days, ok And 0:15:53.960 --> 0:15:56.320 then you know they're going to lay their eggs starting 0:15:56.320 --> 0:15:59.320 on day like four or five, and the eggs only 0:15:59.360 --> 0:16:03.640 take about a day before they hatch, and then they 0:16:03.880 --> 0:16:06.000 feed as larvae for about a week and then they 0:16:06.040 --> 0:16:08.560 pew paint for about a week. And so their whole 0:16:08.800 --> 0:16:12.120 life cycle is maybe what's that like a month a 0:16:12.120 --> 0:16:15.880 little more than a month, Okay, And so you could 0:16:15.880 --> 0:16:19.480 be getting twelve plus rounds, I mean, plus each female 0:16:19.520 --> 0:16:23.200 is laying like three thousands. Yeah, I can't even calculate. 0:16:23.280 --> 0:16:23.720 That's a lot. 0:16:24.640 --> 0:16:28.400 It's just hard to comprehend. Like like they I feel 0:16:28.440 --> 0:16:31.720 like they would run out of living tissue to eat. 0:16:32.000 --> 0:16:36.720 It's an interesting So it's actually really interesting that you 0:16:36.720 --> 0:16:39.200 say that because one of the one of the papers 0:16:39.240 --> 0:16:42.960 that I read was looking at like the overposition behavior 0:16:43.080 --> 0:16:46.200 of these flies, and they were pointing out that, like 0:16:47.120 --> 0:16:49.520 if you look at the way that they overpause it, 0:16:49.720 --> 0:16:52.320 and like how frequently they do it, and how they 0:16:52.400 --> 0:16:54.720 lay their eggs in these like multiple different clutches and 0:16:54.760 --> 0:16:58.480 all of this, but they do it multiple times in 0:16:58.520 --> 0:17:00.280 their life, right, Like a lot of a lot of 0:17:00.320 --> 0:17:02.960 flies or other insects might just lay like one giant 0:17:03.000 --> 0:17:06.240 clutch and then go ahead and die. But the way 0:17:06.280 --> 0:17:10.600 that these particular screwf lines do it, they at least 0:17:10.600 --> 0:17:12.560 in this paper, were saying that this fits with this 0:17:12.600 --> 0:17:19.000 strategy of like exploitation where they might be evolutionarily finding 0:17:19.080 --> 0:17:22.240 niches that aren't always there, right in an environment that's 0:17:22.280 --> 0:17:24.880 not always favorable. And so you've got to be able 0:17:24.920 --> 0:17:27.680 to take advantage lay a whole bunch of eggs as 0:17:27.720 --> 0:17:30.200 soon as you can and as quickly as possible when 0:17:30.240 --> 0:17:31.880 you find the right wound, because you don't know when 0:17:31.920 --> 0:17:38.280 you will again, which suggests that in nature, the perfect 0:17:38.520 --> 0:17:42.080 wound over position site might have been harder to come by. 0:17:43.160 --> 0:17:47.480 But then enter live stock livestock. Yeah, and now there's 0:17:47.480 --> 0:17:52.080 basically free terrain. Because when I before I started researching this, 0:17:52.560 --> 0:17:55.159 and when I thought of like the wounds that screw 0:17:55.240 --> 0:17:59.359 worms were causing, but also that they were first laying 0:17:59.359 --> 0:18:01.879 their eggs in. I always thought of like a huge, 0:18:01.960 --> 0:18:07.520 gaping like wound, right, like some kind of large hole, 0:18:08.240 --> 0:18:12.240 some infected something. But actually that's not the right image 0:18:12.240 --> 0:18:16.959 to have. The types of wounds that these flies can 0:18:17.200 --> 0:18:20.600 overpose it in to begin with, can be as small 0:18:20.640 --> 0:18:22.080 as a tick bite. 0:18:22.320 --> 0:18:25.560 And often are from a tick bite exactly. 0:18:25.680 --> 0:18:28.840 And so it's any break in the skin, a scratch 0:18:29.040 --> 0:18:31.560 from a thorn or a fence wire, like I said, 0:18:31.560 --> 0:18:36.360 the belly buttons of newborn animals insect bites. The wounds 0:18:36.359 --> 0:18:43.640 that can then be caused are incredibly substantial, and animals, 0:18:43.760 --> 0:18:47.360 especially livestock animals, can die within a number of days 0:18:47.400 --> 0:18:53.480 to weeks after infestation with a screwworm or it's multiple screwworms, 0:18:53.840 --> 0:18:58.880 because of how deeply these screwworms can wander and destroy 0:18:59.000 --> 0:19:03.040 tissue along their way, and because of things like secondary 0:19:03.040 --> 0:19:06.800 bacterial infections that can occur from you know, just the 0:19:07.160 --> 0:19:11.800 open wound that is caused by these maggots. So that's 0:19:11.840 --> 0:19:13.960 that's like mostly screwworms arin. 0:19:14.600 --> 0:19:17.320 And Okay, so between the Old World and New World, 0:19:17.480 --> 0:19:21.440 are there differences in the severity or in the number 0:19:21.520 --> 0:19:23.199 of eggs, or you know, whatever it is. 0:19:23.520 --> 0:19:25.399 It's a good question. It was like weirdly hard to 0:19:25.440 --> 0:19:30.800 find great papers on the Old World screwworms. So from 0:19:30.840 --> 0:19:32.960 what I can tell, they they don't tend to be 0:19:33.040 --> 0:19:35.840 maybe quite as severe or at least not as deadly 0:19:35.960 --> 0:19:40.320 as quickly. Okay, Okay, I don't I don't know exactly why, 0:19:40.359 --> 0:19:42.600 Like what are you know, all of the specific differences 0:19:42.640 --> 0:19:47.199 between them, As I know you'll probably talk about, the 0:19:47.240 --> 0:19:50.719 biggest difference in how we've dealt with them is that 0:19:50.760 --> 0:19:54.080 there are not as many programs that are widespread to 0:19:54.160 --> 0:19:56.439 try and eliminate the old world screwworms. So it is 0:19:56.560 --> 0:20:00.560 very much still a problem throughout its distribution. I see, 0:20:00.800 --> 0:20:04.200 whereas we have changed the current distribution of the New 0:20:04.240 --> 0:20:05.840 world screwworm. 0:20:05.480 --> 0:20:08.480 Yeah against us you will. 0:20:08.560 --> 0:20:12.439 Yeah. And then in terms of like how do we 0:20:12.600 --> 0:20:14.840 manage it? Aside from what you're about to talk about, 0:20:14.880 --> 0:20:18.640 I just keep like putting little putting, little teasers out there. 0:20:19.480 --> 0:20:22.640 We don't have any kind of vaccine, we don't have 0:20:22.760 --> 0:20:27.120 any kind of like specific treatment for screwworms. It's basically 0:20:27.200 --> 0:20:32.320 when we're talking about livestock insecticides on the wounds or 0:20:32.400 --> 0:20:35.200 like insecticide dips and things to try and help prevent 0:20:35.240 --> 0:20:38.840 the screw worms infection to begin with, we can also 0:20:39.040 --> 0:20:43.240 use avermectins like ivermectin, so for humans with when there 0:20:43.359 --> 0:20:46.320 is human infection, because there can be, and there there is. 0:20:46.440 --> 0:20:48.639 This is also a public health problem, not just a 0:20:48.680 --> 0:20:53.520 livestock problem. Yep. It requires oral ivermectin. And this doesn't 0:20:53.720 --> 0:20:57.560 like get rid get rid of the infection per se. 0:20:57.680 --> 0:21:00.159 What it does is paralyze the larvae, which then have 0:21:00.160 --> 0:21:02.200 to still be removed thereafter. 0:21:02.600 --> 0:21:06.440 Okay, it paralyzes the larvaie how interesting? Yeah? 0:21:06.880 --> 0:21:13.359 Yeah, So our main stay of dealing with the New 0:21:13.400 --> 0:21:16.800 World screwworm has been sterile insect technique. 0:21:17.160 --> 0:21:19.120 It's so cool prevention. 0:21:19.240 --> 0:21:22.080 Tell me all about it? 0:21:22.119 --> 0:21:22.280 Is it? 0:21:22.800 --> 0:21:23.080 Really? 0:21:23.359 --> 0:21:25.560 Yeah? I don't have any more great. Is going to 0:21:25.600 --> 0:21:26.679 be basic and straightforward. 0:21:26.880 --> 0:21:44.600 I'm excited. All right, let's let's get started. So to 0:21:44.640 --> 0:21:47.199 help me set the stage for the history of screwworm, 0:21:47.520 --> 0:21:49.720 I've brought along some assistance. Aaron. 0:21:49.880 --> 0:21:50.400 I can't wait. 0:21:50.760 --> 0:22:03.119 Please open the video titled screw Worm one. 0:22:03.359 --> 0:22:08.600 Three hundred million years before man appeared on Earth, the 0:22:08.680 --> 0:22:14.199 insect was here with time to develop varieties so diverse. 0:22:14.640 --> 0:22:21.679 Their numbers are beyond conception, roughly a million species along 0:22:21.720 --> 0:22:27.320 with ticks and mites, three fourths of all the animal kingdom. 0:22:28.359 --> 0:22:35.679 Of these ten thousand species are man's mortal fol endlessly 0:22:35.800 --> 0:22:41.240 vying with him for food and fiber, endlessly looting what 0:22:41.400 --> 0:22:43.080 he has sown and ended. 0:22:51.600 --> 0:22:54.400 Did you like that? I loved it, Aaron. I really 0:22:54.440 --> 0:22:56.680 hated the grub Those were grubs, not maggots. 0:22:57.000 --> 0:23:00.720 Listen, the video is like everything grubs country. 0:23:00.920 --> 0:23:02.080 Yeah, that was clear. 0:23:02.240 --> 0:23:04.920 It's so fun so that I loved it so much. 0:23:05.000 --> 0:23:08.000 That video is from It was produced by the US 0:23:08.000 --> 0:23:11.400 Department of Agriculture, the usd DA in nineteen sixty nine, 0:23:11.880 --> 0:23:13.879 and it goes into some of the various like insect 0:23:13.960 --> 0:23:19.320 and plant pests screwworm that I've been plaguing farmers across 0:23:19.320 --> 0:23:21.600 the globe. I also thought it was interesting because it 0:23:21.680 --> 0:23:24.800 was like one million species, and I looked it up 0:23:24.840 --> 0:23:27.160 and I think we're now at like five point five 0:23:27.200 --> 0:23:30.520 million species. One million is such an underestimate, right, It's 0:23:30.520 --> 0:23:33.520 like doctor Evil, like one million dollars. Like that's kind 0:23:33.520 --> 0:23:35.120 of what it reminded me. 0:23:35.480 --> 0:23:35.760 See. 0:23:36.480 --> 0:23:41.000 Yeah, but Yeah, I went all in on video clips 0:23:41.000 --> 0:23:43.320 for this episode you're about to find out. So, Yeah, 0:23:43.359 --> 0:23:48.400 there's an amazing archive work at the National Agricultural Library 0:23:48.440 --> 0:23:51.639 on the USDA website and as well as the Internet archive, 0:23:51.640 --> 0:23:55.040 which is just one of my favorite things in existence. 0:23:55.119 --> 0:23:58.840 But but I wanted to start the history of screw 0:23:58.920 --> 0:24:01.960 worm with that clip because I feel like it transports 0:24:02.000 --> 0:24:04.520 us back to a time when New World screw worm 0:24:04.640 --> 0:24:07.879 was among the top threats to agriculture here in the US. 0:24:08.640 --> 0:24:11.160 And by the way, I'm going to just be focusing 0:24:11.200 --> 0:24:14.280 pretty much only on New World screw worm for this 0:24:14.640 --> 0:24:16.840 which I'm just calling screwworm for short. 0:24:16.960 --> 0:24:18.680 That's what most of the literature does. It's fite. It 0:24:18.720 --> 0:24:20.280 was hard for me to find stuff on old world 0:24:20.359 --> 0:24:20.880 screw worm. 0:24:21.160 --> 0:24:25.639 Yeah, but it's eradication from North and Central America in 0:24:25.720 --> 0:24:29.400 nineteen ninety one, which spoilers it was eradicated and spoilers 0:24:29.440 --> 0:24:33.920 it's back. It marked a tremendous achievement in pest control 0:24:34.119 --> 0:24:37.360 and a demonstration of what was possible without the use 0:24:37.400 --> 0:24:41.359 of toxic pesticides. It was a big deal. Hence the 0:24:41.400 --> 0:24:44.200 sheer volume of material that's out there about the screw 0:24:44.200 --> 0:24:48.320 worm eradication program, and after it was eradicated, it dropped 0:24:48.320 --> 0:24:50.440 out of the news cycle for the most part, except, 0:24:50.600 --> 0:24:52.720 of course, in the places where it was still prevalent, 0:24:52.840 --> 0:24:57.360 like most of South America, and the recent headlines about 0:24:57.400 --> 0:25:01.200 the reemergence of screwworm here in the US that might 0:25:01.240 --> 0:25:03.560 be the first time that many people have learned about 0:25:03.640 --> 0:25:06.760 or heard of this parasite, but in fact, it has 0:25:06.880 --> 0:25:13.040 plagued wildlife, humans, livestock in the Western Hemisphere for thousands 0:25:13.080 --> 0:25:17.720 of years, and so using genetic analyses, researchers recreated the 0:25:17.800 --> 0:25:20.679