Seed bug, Melacoryphus lateralis
Photo: OPSU
Much of the Southwest US has been plagued with large swarms of seed bugs. These seed bugs are
Melacoryphus lateralis a bug that has periodically had large populations in Arizona, but not such large populations elsewhere until this year. This is a different bug than the
Elm Seed Bug,
Arocatus melanocephalus, an invasive species recently found in Southwestern Idaho. Some recent comments on the Elm Seed Bug post probably refer to
Melacoryphus lateralis. Many bugs in the family Lygaeidae have black and orange/red coloration making them difficult for amateurs to differentiate.
Melacoryphus lateralis is not the same as the round greenish bug that is causing issues near Black Rock, NV.
Scientists from Arizona say that this is the largest outbreak of Melacoryphus lateralis in 30 years. The intense drought in the western US has diminished food sources for the bugs. When food becomes scarce, bugs migrate if that have the capability.
Seed bug swarm, Melacoryphus lateralis
Photo: Matthew Hengst
Seed bugs aggregate around lights and areas that are irrigated or naturally have more moisture than the surroundings. Those who are not bug lovers are annoyed by the bugs crawling everywhere and invading houses. Control is not possible. Historically, boom populations are followed by a crash and the outbreak will cease. Those who admire insects are awed by the impressive swarms.
About jjneal
Jonathan Neal is a retired Associate Professor of Entomology at Purdue University and author of the textbook, Living With Insects (2010).
This blog is a forum to communicate about the intersection of insects with people and policy. This is a personal blog.
The opinions and materials posted here are those of the author and are in no way connected with those of my employer.
Living With Insects Blog 
Pingback: Attack of the Seed Bugs
thank you
We have these right now in Southern California. Thousands of them! Sickening pest!
I moved from Southern California, Menifee. I moved to Michigan and I found an infestation of these in or near an old tree stump. I spayed them, but wasn’t sure if that was the right thing to do (?)
Good luck!
I have them in southeast Michigan
I eradicated them from my kitchen by using Roach Away under the sink in the crack between the wall and the bottom of the cabinet, then under the fridge, dishwasher, and stove. They haven’t come back. Haven’t figured out how to get rid of then from the rest of the house. Not a lot fortunately.
They do congregate around my light by the door in the evening.
I found an infestation of these bugs in a dead tree in the yard. I was weeding around the tree, and when I pulled up the roots, there was an infestation of so many of these things. I use a lot of insecticide on them. I didn’t know what to do and it scared me, was that the wrong thing to do? It looked like a mound of red ants or something but it wasn’t ours. It was these bugs but a lot of them! I am in Ottawa county Michigan I am moved from California, so this is very confusing.
There are many species of seed bugs. The ones you saw are most likely endemic.
In Michigan, box elder bugs are common and similar in appearance. They do go indoors to overwinter. They can be a nuisance but are not otherwise harmful