Things often mistaken for eggs

See also: Beetle Eggs • Moth Eggs • Butterfly Eggs • Hemiptera Eggs

I occasionally go through the Eggs & Egg Coverings of Terrestrial Invertebrates collection and kick out things that are not actually eggs. Along with some obvious things that shouldn't be marked as eggs and that were probably mis-clicks, I also find annotations that are the result of common misconceptions. In particular, plant galls, pupae of parasitic wasps, pupae and larvae of ants, plant-parasitic hemipteran nymphs and females, spittlebug foam, and case-bearing leaf beetles turn up in the eggs collection pretty much on a daily basis. Below are are some pointers to help budding naturalists avoid these annotation traps:

• Plant Galls
• Ichneumonoid Pupae
• Ant Pupae & Larvae
• Plant-parasitic Hemipteran Nymphs & Females
• Spittlebug Foam
• Case-bearing Leaf Beetles

If you want to help clean up the iNat egg annotations, here are some quality control queries to check for common egg annotation errors. If you see any observations that are wrongfully annotated as eggs, please give the egg annotation a thumbs down. You can also link to this post, if you think it will help prevent similar mis-annotations in the future. If you know of other common mis-annotations of eggs, let me know and I will add them to this list.

• Plant Galls should be annotated as eggs only if the presence of an egg is documented in the observation:
  Observations annotated as both galls & eggs
  Cynipidae observations annotated as eggs
  Cecidomyiidae observations annotated as eggs

• Ichneumonoid observations annotated as eggs. Are they really eggs?
• Ant observations annotated as eggs. Are they really eggs?
• Plant-parasitic Hemiptera annotated as eggs. Are they really eggs?
• Spittlebugs annotated as eggs. Are there really spittlebugs eggs or just a foam mass?

Plant Galls

While some galls are somewhat egg-shaped and may therefore be mistaken for eggs, even galls that don't resemble eggs at all are often annotated as eggs. It seems that some people think that galls are egg coverings or that insects oviposit into galls. While a few hyperparasitic wasps indeed lay eggs into the galls of other insects, this is rather the exception. In most cases, the gall is induced upon oviposition or by the activities of the larva or nymph, so when you see a fully formed gall, the organism has long since hatched from its egg.

Don't be fooled! There's no evidence of eggs here. Please don't annotate galls as eggs unless you have cut them open and actually found an egg. Just annotate them as Evidence of Presence - gall and leave it at that. Images by @treegrow, CC-BY.

Ichneumonoid Pupae

The pupae of some parasitic wasps are encased in egg-shaped silk cocoons that are often wrongly annotated as egss on iNaturalist. For example, the ichneumonid subfamily Campopleginae has egg-shaped pupal cases that are usually suspended from a leaf or twig by a silk thread (see image below). Once you have looked at a few of these you should be able to recognize them, so you'll never mistake them for eggs again.

Pupae of parasitic wasps. (1) The ornate silk cocoon of a campoplegine pupa. (2) A caterpillar covered in cocoons of microgastrine pupae. (3) A mass of microgastrine pupae without a visible host. Images by @treegrow, CC-BY.

In the braconid subfamily Microgastrinae, many larvae may feed in a single host, usually a caterpillar. Once they are ready to pupate, they will exit the caterpillar, spin their cocoons and pupate directly on the host. This will then look like a caterpillar with a bunch of "eggs" attached (see image above), but the "eggs" are actually silken pupal cases with tiny, developing wasps inside. Sometimes, there are so many wasp larvae in a caterpillar, that there's nothing left of the host and all you see is a fluffy ball of silk cocoons.

Ant Pupae & Larvae

Ant eggs are tiny. They are generally smaller than the head of an ant. If you open up an ant nest and see a bunch of "eggs" that are almost as big as the ants or even bigger, those are probably pupae or larvae. Please don't annotate them as eggs!

(1) Ant queen with tiny eggs (by @sunnyjosef, CC-BY). (2) Ant workers with larvae (by @ryanhodnett, CC-BY-SA), right. Larvae don't have legs or antennae and are usually shiny and often translucent.

(1) "Naked" ant pupae (by @arnim, CC-BY), distinguished from larvae by the presence of legs & antennae. (2) Ant pupae covered with a rigid, opaque silk cocoon (by @reiner, CC-BY-NC-SA).

Plant-parasitic Hemipteran Nymphs & Females

The nymphs of plant-parasitic hemipterans (aphids, white flies, scale insects, etc.) are often quite sessile and sometimes resemble eggs. In particular, aphids that are parasitized by wasps in the braconid subfamily Aphidiinae often look like little paper eggs as they turn into rotund mummies due to swelling and hardening of their integument. If you look closely, it's usually fairly easy to recognize that these are nymphs and not eggs. Eggs rarely appear segmented and never have legs or antennae.

(1) Whitefly nymphs on the underside of a leaf (by @nicz, CC-BY-NC-SA). (2) Mealybug nymphs on a shrub (by @treegrow, CC-BY). (3) Aphid nymphs on a tree (by @treegrow, CC-BY). (4) Parasitized aphid mummies among their skinnier unparasitized siblings (by @pfau_tarleton, CC-BY-NC).

Things get a little bit more difficult if the organisms produce waxy protective scales that resemble eggs. Many plant-parasitic hemipteran nymphs and females do this. In those cases, you just have to know the difference between an egg and a nymph or female, although size often helps. Most insect eggs are tiny, nymphs are usually a bit larger, and females larger still.

(1) Egg-shaped adult female soft-scale. (2) Wax-scale female (bottom right) and nymphs. (3) Adult female armored-scale. Images by @treegrow, CC-BY.

Things get a little bit more complicated though when you consider that some scale insect females produce waxy secretions on their bodies that function as egg sacs. So in these cases, it would be ok to annotate the observation as eggs if you wanted to focus on the egg sac. But please don't add annotations for both the egg sac and the female to the same observation. Instead, create two separate observations, one for the egg sac and one for the mother.

Female scale insects with egg sacs. (1) Pulvinaria. (2) Icerya purchasi. Images by @treegrow, CC-BY.

Spittlebug Foam

Spittlebug foam masses are often misinterpreted as egg coverings. However, the protective foam is produced by a nymph, so there are never any eggs in these "bubble nests." Spittlebug nymphs are xylem feeders. They consume large amounts of plant sap and then blow liquid waste out their anus after enhancing it with foam-producing secretions. The resulting foam mass protects the nymph from potential predators until it has completed development and emerges as a winged adult.

(1) A spittlebug foam nest on a leaf. (2) If you clear away some of the foam, you'll see the spittlebug nymph underneath. (3) A winged adult spittlebug. Images by @treegrow, CC-BY.

Case-bearing Leaf Beetles

The larvae of some case-bearing leaf beetles live in egg-shaped, protective cases made from fecal matter and plant debris. When the larva moves around, you can see tiny little legs emerge from the case, so it's pretty easy to see that it's not an egg. But before each larval moult and when it gets ready to pupate, the larva will seal the opening of the case and sometimes it will also apply a few threads of silk to fasten it to
a leaf. When the larva/pupa sits still like this, it may easily be mistaken for an insect egg.

(1) A casebearer larva on the move. When they are walking around like this, it's easy to see that they are not eggs (by @yawwhite CC-BY-NC).
(2) A closed casebearer case stitched to a leaf, looking very egg-like (by @treegrow, CC-BY).

Posted on July 17, 2023 12:19 AM by treegrow