I didn’t mean to make two “what the heck is this?” posts in a row, but it’s the first of the month and therefore time for another Monthly Mystery. This one is an egg mass I found on a manzanita (Ericaceae: Arctostaphylos) leaf in Madera Canyon, Arizona on November 7. At first glance, the white secretion covering the eggs gave the impression of a bird dropping. The mass is 12 mm long.
If you look closely at the above photo, you may notice a small yellowish bug that looks as though it could have hatched from one of the eggs, but no, it’s just a thrips. If you look closely enough at any surface you’ll probably find a thrips there.
Margarethe Brummermann found a similar egg mass, also in Arizona, last July. Those eggs had already hatched too. I’m not sure that much can be said about the phenology of the insect that produces these, based on these two data points.
Troy Bartlett has also found something somewhat similar in Brazil, though the covering in that case was brown rather than white. As I suggested on Troy’s blog, the way these eggs have neat little oval lids that pop off is highly suggestive of true bugs (Heteroptera), and their shape and orientation specifically reminds me of leaf-footed bug eggs (Coreidae); however, I’m unaware of any leaf-footed bugs that cover their eggs with a secretion. The only true bugs that I can think of that do this are assassin bugs (Reduviidae), but both the eggs and the secretions are pretty different in the examples I know of (e.g. Phymata and Zelus). If there are families of mostly tropical true bugs with distributions that extend into Arizona, they would seem to be likely suspects.