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Caterpillars feed and grow in their cases (first pic) before emerging as winged adults (second pic). The fact that both sexes look similar as flying moths might seem obvious but they stand as an important contrast to later-diverging, highly sexually dimorphic bagworms.

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But in the cloudforests of Costa Rica, we found bagworms feeding on fungus in rotting logs and making these long, slender sawdust cases! I promise there's a caterpillar in there but it might not be as big as you think...

If you know bagworms, it's probably for cases like this one (from Abbot's bagworm) made of sticks and leaves tied together with silk as they feed on host plants.

Andrew Mongue @ajmongue.bsky.social · 04/09/2026

What's going on here? Is that fungus? Noodles?? No, it's bagworm moth cases! In a new article led by co-advised student David Cheng, we describe two new species and a whole new subfamily of bagworm moths: Tenuipsychinae! academic.oup.com/isd/article-... Brief explainer below!

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It turns out Varroa mites aren't haplodiploid after all!?

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We also get insights into chromosome evolution, finding a single X chromosome in the ambush bug, as opposed to the X1X2 system of other assassin bugs. Thanks to coauthors @tliesenfelt.bsky.social and Paul Masonick for their work on the molecular methods and taxonomy! 5/5

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For instance, the protein composition of the saliva of blood feeding assassin bugs like the kissing bug is well characterized. By searching the genome of the ambush bug, we show that most of those proteins were likely already present in the predatory ancestor of the bloodfeeders. 4/5

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In this paper we generated a chromosome level genome assembly for Phymata mystica, a predatory outgroup to more (in)famous blood feeding assassin bugs. This evolutionary relatedness but ecological difference makes it a valuable point of comparison. 3/5

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Andrew Mongue @ajmongue.bsky.social · 13/07/2026

New Mongue lab publication alert! The first first-author paper for master's student @ethangrebler.bsky.social who started this work as an undergraduate in the lab! The genome assembly of the ambush bug Phymata mystica! Read about it here: academic.oup.com/g3journal/ad... Highlights below 1/5

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Reposting a great response to a recent viewpoint piece bends over backwards to argue "that sex is always binary*,**" *But only if we define systems with more than two sexes as "not sexes" (mating types) **And only if we define binary as "not always binary" [See screenshots] 1/3

Andrew Mongue @ajmongue.bsky.social · 27/06/2026

And if I'm reading this correctly, this is the "cancel active grants at any time based on political whims" provision from OMB.

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All of this work is united thematically (evolutionary reproductive biology) but also enabled by our modified approach to Hi-C sequencing that lets us get chromosomal level assemblies from tiny, rare insects. Ask us about it if you're interested. See you soon, Cleveland! 5/5

Finally, PhD student Christina @clwatkins.bsky.social intros our new model system for evolution of sexual dimorphism Bagworm moths: a new model for studies of genome evolution across variable levels of sexual dimorphism Sexual Selection and Conflict June 23, 2026 4:45 PM - 5:00 PM 4/5

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Next, I'll be presenting a big update on sex determination turnover across scale insects Leaving X: How scale insects repeatedly evolved alternatives to chromosomal sex determination Me! Reproductive Biology June 22, 2026 10:15 AM - 10:30 AM 3/5

Up first: recent undergrad/soon to be master's student Ethan previews resources we've generated for a rare group of Neuroptera with unique life history and chromsomal dynamics: Mantispidae. The Secrets of the Mantidfly Genome Ethan Grebler Bioinformatics June 21, 2026 5:00 PM - 5:15 PM 2/5

Andrew Mongue @ajmongue.bsky.social · 10/04/2026

The full Mongue lab will be at #evol2026! Say hi or come see our work. All three of us have talks (pic related). Check this thread for some more specifics and we hope to see you there! 1/5

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The Mongue lab and Kawahara lab @dr-akito.bsky.social are hiring postdocs!! If you're interested in the genomics of extreme sexual dimorphism and/or silk production, come work on bagworms with us! See below for details: sicb.org/jobs-and-fel...

An Abbot's bagworm case made of silk and sticks

Adult female bagworm (left) and males (right).

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This is the biggest project in my lab so far and wouldn't have been possible without help from lab members and collaborators @tliesenfelt.bsky.social @erincpow.bsky.social @kkbugtime.bsky.social And my former postdoc adviser @laurarossevo.bsky.social for introducing me to scales. Thank you!! 7/7

The Mongue lab at a conference last year.

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The other loss, for PGE, is very different. Here, the X is basically intact across the transition and for several PGE groups. The biggest rearrangement only happens in true mealybugs, Pseudococcidae. In other words, the X chromosome seemed to be supplanted not lost. What does it all mean? 5/n

Synteny across loss of X sex determination for paternal genome evolution. Colored bars next to species are chromosomes with individual colored lines tracking gene conservation between species. Where applicable, the X is the leftmost chromosome and highlighted with a dashed box.

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Next, we explored genomic changes across transitions. Starting with the hermaphrodites we found that the X fused to one of the 2 massive autosomes and gene order became more shuffled within and between chrs. Weirdly, the decrease in chromosome number precedes the turnover and may help enable it? 4/n

Synteny across loss of X sex determination for simultaneous hermaphroditism. Colored bars next to species are chromosomes with individual colored lines tracking gene conservation between species. Where applicable, the X is the leftmost chromosome and highlighted with a dashed box.

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First, we reconstructed a big phylogeny of scale insects based on ~1500 genes. We found X sex determination is ancestral (and some scales still use it!) and there have been 2 independent losses of the X, once in the hermaphrodites and again in the paternal genome eliminating clade. 3/n

Maximum likelihood phylogeny of scale insects colored by sex determination system. Tips with a * are newly sequenced draft genomes, those with an illustration are new chromosome level assemblies.

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Andrew Mongue @ajmongue.bsky.social · 09/12/2025

I'm back with another weird scale insect repro study. Previously I've talked about the simultaneous hermaphrodite cottony cushion scales and (functional) haplodiploidy paternal genome elimination in mealybugs. But how did these systems evolve? The Mongue lab has some answers! 1/n #genomics

An unknown scale insect from Costa Rica.

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To explore this, we've done genomics, proteomics, and a bit of cytogenetics on the evergreen bagworm. The one sperm type looks basically like fertilizing sperm, but with some differences from other lep sperm proteomes, like a lack of proteases to break apart bundled fertilizing sperm.

Conservation of sperm proteins across Lepidoptera. Proteins in the blue subsets are found in fertilizing sperm, those in red are from non-fertilizing sperm, and those found in both are at the overlap. Orthologous evergreen bagworm sperm proteins come (almost) entirely from the fertilizing and shared subsets.

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Andrew Mongue @ajmongue.bsky.social · 09/12/2025

But we're most interested in the adults. In this pic, the grub-like insect is an ADULT female bagworm(!!). The males look like normal moths...extreme sexual dimorphism!! We're studying how this evolved, but that's another story. Today I want to highlight their sperm biology.

A grub-like female and two male evergreen bagworms.

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Andrew Mongue @ajmongue.bsky.social · 09/12/2025

Pre-print and weird repro thread time! I've posted here about scale insects a lot, but ~half of my research is on Lepidoptera. My lab is developing bagworm moths (Psychidae) as models for comparative genomics. You probably know them like you see in the pics below: caterpillars that make cases.

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Andrew Mongue @ajmongue.bsky.social · 22/11/2025

This thread needs the Bible...the Perry Bible Fellowship.

A pedantic penguin very much not helping the cause.

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Andrew Mongue @ajmongue.bsky.social · 14/11/2025

Talk about a life list critter, I've finally found a male cottony cushion scale insect (pic 1)!! Male scale insects are rare in general but this species is composed almost entirely of simultaneous hermaphrodites (pic 2)! Rare pure males can occur, but we don't fully know under what conditions.

A hermaphrodite cottony cushion scale upside down on a leaf.

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Andrew Mongue @ajmongue.bsky.social · 10/11/2025

The now traditional Mongue lab and alums photo from #EntSoc25. Crazy how much the lab has grown in two years!

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Andrew Mongue @ajmongue.bsky.social · 04/09/2025

Lab milestone: My first (now graduated) student's first genome assembly is now publicly available! Well done, @tliesenfelt.bsky.social !! You can read the companion article below!

Screenshot of NCBI genome database showing the newly added mealybug genome.

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Andrew Mongue @ajmongue.bsky.social · 09/07/2025

Such a fun and productive trip! Be on the lookout for more on evolutionary genomics and systematics of bagworms from my lab and @dr-akito.bsky.social 's lab soon!

Andrew Mongue @ajmongue.bsky.social · 19/06/2025

Getting ready for #Evol2025. If you see me say hi! I'll be doing a very preliminary talk on bagworm moth evolutionary genetics on Sunday at 11:45 as well!

Two evergreen bagworm larvae on juniper.

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Andrew Mongue @ajmongue.bsky.social · 12/06/2025

Well if that's the game of the game...here's a shot of Fulgora lanternaria from a recent trip to Costa Rica.

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Andrew Mongue @ajmongue.bsky.social · 02/06/2025

How do you differentiate species when the most visible lifestage is a featureless brown rugby ball? You sequence it and place it with phylogenomics! Read all about this and the evolutionary genetics of a moth-infecting apicomplexan #parasite in our pre-print here: www.biorxiv.org/cgi/content/...

Brown, oval oocysts are the most visible lifestyle of the Helicoverpa-infecting Ophryocystis. Sorry for the lack of scale bar!

Sequencing places this parasite (outlined in green) as sister to the Ophryocystis that infect milkweed butterflies.

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Andrew Mongue @ajmongue.bsky.social · 23/05/2025

Some more mantidfly mania for #WorldBiodiversityDay These two were photographed in Costa Rica, where my lab is currently doing fieldwork (more on that soon)!

A mantidfly, possibly Trichocelia banksi, pointing upward

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Andrew Mongue @ajmongue.bsky.social · 17/04/2025

You can divide a hot minute by 60 and it has the same value, baffling

Andrew Mongue @ajmongue.bsky.social · 08/04/2025

This is far from the most salient problem with the new "dire wolves," but while we're all dogpiling this story...they couldn't even name the female pup Arya or Sansa? They went with the title (not even name) of the war crimes dragon lady...absolute hacks

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Andrew Mongue @ajmongue.bsky.social · 14/02/2025

Excited to announce another genome preprint! This one is first-authored by my first master's student, Tracy! We generated a chromosome level genome for the invasive hibiscus mealybug, a citrus crop pest. Thanks to coauthors @lmdiepenbrock.bsky.social @kkbugtime.bsky.social tinyurl.com/5n8h42r6

Hibiscus mealybug damage on citrus fruit

Close up of female with wax egg case (top left) male (top right) and illustrations of both (bottom)

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Okay wrapping up: this odd genetic system creates contrasting evolutionary dynamics for the sexes. How do these patterns extend to longer evolutionary time? More soon, stay tuned to the Mongue lab as we continue exploring paternal genome elimination and other weird repro! 7/7

A bunch of citrus mealybugs on a sprouting potato.

If we look at the amount of adaption involved (let's save the pop gen methods for a future thread?), the pattern reverses: female-biased genes evolve less adaptively than those expressed in males! Why? Because haploid selection slows evolution but also removes more weakly deletetious variants. 6/n

The proportion of adaption substitutions (alpha) in genes by sex-bias class. Female-biased genes evolve less adaptively than genes expressed in males.

So different dynamics for the sexes and lots of sex-specific gene expression? This creates differing evolutionary trajectories for genes. First, genes expressed partly or entirely in males more slowly than female-biased genes. Evolution is faster on the female side in mealybugs! But.. 5/n

Boxplot of scaled divergence (dN/dS) split by sex-bias. Genes expressed in both sexes are the slowest evolving, followed by male-biased genes, then female-biased genes evolve the fastest.

As you've maybe noticed, males and females are highly sexually dimorphic! Males are small, winged, and don't eat as adults. Females are large, sessile, and long-lived. This dimorphism extends to gene expression as well. Most genes are expressed in one sex or the other, but not both. 4/n

A histogram of the proportion of gene expression limited to one sex. The highly bimodal distribution means that most genes are sex-biased in expression.

This dynamic has two consequences: (1) males express genes in a haploid state, which should create more efficient selection than in diploids (2) fathers cannot pass on genes directly to their sons. They have to pass through a daughter to end up in a grandson. 3/n

Diagram showing expression and transmission of genes expressed in males, females, or both sexes. In males genes are expressed in a haploid state. In females, a diploid state. Furthermore, males never pass on genes directly to their sons.

Mealybugs are sexually reproducing but have no sex chromosomes. Sex is determined by whether an embryo expreses 1 or 2 copies of the genome, so haplodiploidy BUT unlike other haplodiploids, eggs that develop male are fertilized too. They just eliminate their paternally inherited chromosomes! 2/n

A diagram of paternal genome elimination showing how the paternal genetic contribution is discarded from male embryos during development.