Dobsonfly Structural Adaptations: 9 Tips To Surviving in The Water

Dobsonflies live as aquatic insects most of their life and have uniquely adapted to their environment. Here are some dobsonfly structural adaptations and what benefit they derive from them

Structural adaptations are one of the most amazing things about the world of insects. If you’re fascinated by how different insect species adapt to their environments and life cycles, this article is for you. 

Let’s check out what structural adaptations you can find in a dobsonfly, which, by the way, happens to be the largest aquatic insect in the world.

Feeding

1. Larvae Have Strong Mouthparts to Bite Prey

The most noticeable features of dobsonfly larvae are their large and strong mandibles. 

They are voracious aquatic predators that prey on other aquatic insects, larvae, and small fish. The strong mouthparts allow them to rip their prey apart.  

2. Use Touch and Chemical Sensing to Find Prey

As mentioned above, dobsonfly larvae are carnivores and hunt other aquatic creatures. 

They locate their prey using both touch and chemical sensing. However, they also have eyes and are at least capable of identifying motions and shadows.

3. Terminal Hooks To Hold Themselves in Running Water

If you look closely at a hellgrammite (dobsonfly larva), you’ll notice a pair of hooked appendages on its terminal end. 

These hooks serve an important purpose in their hunting technique. These larval insects mostly hunt in fast-flowing water, which means they’re always at risk of getting swept away in the current. 

These terminal hooks allow the ambush predators to hook themselves to rocks or other surfaces while it hunts or feeds.

4. Larvae Can Swim Both Backwards and Forwards

An interesting fact about dobsonfly larvae is that they’re capable of swimming both forward and backward by undulation. 

This further enhances their hunting capabilities by enhancing their mobility in the water. However, they don’t swim often – they mostly crawl along surfaces.

5. Adults Don’t Feed

The feeding habit of adult dobsonflies is quite contrary to the aggressive predacious nature of their larvae – they don’t eat any solid foods. 

While adult male dobsonflies don’t feed at all, the females sometimes feed on nectar from flowers. Not needing to feed is indeed a nice perk for these bugs.

Mating

6. Elongated Mandibles For Fighting

While hellgrammites use their strong mandibles to prey and feed, the winged adults have a completely different purpose for these appendages contesting for a female. 

Adult male dobsonflies grow elongated, sickle-shaped mandibles. They fight rival males by hovering over them aggressively and trying to grab and flip them using these mandibles.

Besides, female dobsonflies also find males with longer mandibles more attractive. This is another way how the mandibles help male dobsonflies gain the upper hand when contesting for a female.

7. Scent Glands and Touch During Mating

Like many other bugs, dobsonflies use scent to communicate with potential mating partners. There are scent glands on the abdomen of male dobsonflies that help them in mating. 

Touch plays a role in their communication and mating ritual too. Male dobsonflies place their mandibles on the females while courting them.

8. Nuptial Gifts

At the end of a mating session, a male dobsonfly produces packages of nutrient-rich spermatophores as nuptial gifts for the female. 

However, not all genera of dobsonflies produce nuptial gifts. 

The size of the packages is inversely proportional to the size of the mandibles. Dobsonfly species that boast the biggest mandibles produce the smallest sperm packets or do not produce them at all.

Breathing

9. Larvae Can Breathe on Both Land and Water

The larvae are aquatic, but that does not mean they cannot breathe on land. 

Their bodies are highly adapted to their aquatic habitats, and they’re capable of absorbing an abundant amount of oxygen from the water. 

They do this using the several tracheal gills they have on either side.

Here’s a quick explanation of how dobsonfly larvae breathe underwater. They have eight pairs of appendages on their sides, which resemble legs but have gill tufts at their ends. 

These feathery gills increase the surface area that the larvae can use to absorb oxygen. They also have a set of puffy gills similar to dandelions, which they can wave in the water to extract more oxygen.

But the unusual aspect is that, in addition to the gills, hellgrammites also have spiracles that they can use to breathe directly from the air when they’re on the surface. 

Their choice of habitat helps them in respiration – fast-flowing and shallow waters contain higher amounts of oxygen.

Frequently Asked Questions

Conclusion

If you live near a water body in North America, there’s a chance that you might encounter Eastern Dobsonflies in your home. 

Although it’s uncommon, these insects sometimes lay their egg masses in pools too. Finding dobsonflies in or around your home indicates a relatively clean environment, as these insects avoid polluted waters. 

Thank you, reader, and I hope you enjoyed reading about the amazing structural adaptations of these huge bugs.