My friend Bryan sent this photograph of a branch on a baby crabapple, thinking it might be a scale insect as INaturalist proposed but an alternate possibility was insect eggs. I suggested he peel one off to test its consistency and attachment, then cut it open carefully with a razor blade to see what is inside. Here is what he found:
"They are layered up like 7mm scales, with the bottom of the teardrop attached and the top of the teardrop overlapping the scale above. Using a razor blade, the answer is --- A bunch of yellow, very runny goo. Unfortunately there is no discernible morphology inside the egg. I wonder if they need more time to mature."
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| Closeup- Click to enlarge |
Meanwhile I sent the picture on to Chris Barnhart who identified them as eggs of a katydid, "probably in the genus Microcentrum." While I can't identify these further without raising them, it lead me down a Covid-induced deep rabbit hole. After looking a a number of katydid egg photographs, I settled on the greater angle-wing katydid (GWA) as the best example to study. This is Microcentrum rhombifolium described here in Bugguide. An example of GWA eggs is below and you can see others here.
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Sticking with GWA as a tentative ID I made a much deeper Googling dive and came up with this information from Illinois.
"The lifespan of a katydid is about a year. Females usually lay their eggs at the end of summer. Most katydids overwinter in the egg form. The males have sound-producing organs on their front wings. They use this sound for courtship. During courtship there often is antennal contact between male and female.
Katydids are eaten by birds and mammals and may be the target of insect predators and parasites including horsehair worms, wasps and flies. This species is common in trees. It can be found in forests, urban areas and edge habitats. The eggs are glued in double rows on the sides of twigs roughened by biting."
Their "song" is produced by stridulation when a scraper is dragged across a set of ridges, much like dragging a phonograph needle across a record. (For those of a younger generation, substitute dragging a fingernail across a comb). Songs of insects has a good description of the GWA and a recording of the high pitched song, so listen carefully.
So what is the risk of waiting to see what emerges? "Although rare, leaf damage, particularly to young trees, can be extremely severe. " Texasinto They can be a significant problem in citrus groves. I suggested to Bryan that he cut and bag the stem and see what emerges. Meanwhile you can see the whole lifecycle in these photographs on Bugguide.
Covid reminder to self: Avoid the news, put down computer and go for a long walk.
