Reading the Book (AKA: It’s not lice)

Since we recently talked about springtails, let’s talk about another common pest that is often confused with springtails. They are found in many of the same places and under the same conditions as springtails. If you guessed psocids, you’re right. If you’ve ever been inspecting a food warehouse or a client’s pantry and seen tiny, pale specks scurrying across a pallet of flour or a dusty shelf, you might have encountered these.

They often get called booklice, which is one of those unfortunate common names that is a bit confusing. Let’s clear the air: they aren’t "lice" (they don't bite or live on people), and while they can be found in old books, there are so many common places they are found in such as food processing.

Psocids are tiny (usually under 2mm), but if you get them under magnification, you’ll notice they have a very distinct, bulging forehead (the clypeus). It looks like they have a giant nose or a grill plate on the front of their head. They also have long, thread-like antennae. Unlike those springtails we talked about previously, psocids don't jump. They just run. If it leaps, it’s a springtail; if it just "scurries" like a miniature cockroach, you’re likely looking at a psocid

But what about the books? These got their name because they were found in old libraries, typically in basements. They weren’t feeding on the books, they were feeding on the starchy glues that were in the book bindings. Being in the dank basements, there was also plenty of mold to feed on. In most cases, psocids are actually a symptom, not just a pest.

They aren't necessarily there for the food in processing facilities and kitchens; they are there for the mold growing on the food product or around the products. This is still a contamination issue, and raw ingredients and finished products can be rejected by customers because these tiny insects are in the shrink wrap around the products or on tape. It doesn’t help that, because they are small and pale, people often mistake them for grain mites or even larval stages of more serious stored product pests.

Of course, what everyone wants to know is if we find psocids what do we do? The first thing to do is check the humidity. If it’s above 50-60%, the facility has created a psocid buffet.  Sometimes psocids arrive on "green" (newly made) wooden pallets that are still holding internal moisture. The wood grows a tiny bit of mold, and the psocids follow. It’s not always possible to reduce humidity, especially in large facilities. Sometimes adding in air movement with fans can be helpful.

Temperature can also have an impact. Is the product touching a cold wall? Condensation forms where warm air hits a cold exterior wall. That moisture is all a psocid needs to start a very large family. Lower temperatures can slow down their life cycle though. So at least that can help with control.

If you have a psocid "outbreak," fogging isn’t going to help. It will knock down some of the exposed ones, but it won’t reach a significant number of them to have a measurable effect. It won't work long-term if you don't solve the environment. However, sometimes some crack and crevice treatment with a residual can help, ONLY if it is in combination with reducing the food source.

Don’t forget FIFO (First In, First Out): Old product is more likely to have settled dust and microscopic mold. Rotate that stock!

The Bottom Line: Don't let the name "booklice" fool you. They are moisture-loving scavengers that are telling you a story about your facility's environment. If you listen to what they’re saying about the humidity, the puzzle gets a lot easier to solve. If you need a “pest translator”, contact me, we can help you with that!

Lagniappe – just a psocid doing psocid-y things.