Insect Diagnostic Laboratory

This week you might be seeing the large cicada killer wasps flying around your yard. Cicada killer wasps have black and yellow abdomens, rust colored wings and are about 2 inches long.Female cicada killer wasps capture cicadas in July and August and place them in cells located at the ends of tunnels they have dug in the ground. One or two paralyzed cicadas are placed in each cell, and a single egg deposited before the cell is closed by the female. The wasp grubs feed on the cicadas and develop into wasps that emerge the following summer.

Cicada killer wasps are intimidating because of their size, but they are not aggressive wasps and will only sting if mishandled.  Control of cicada killer wasps is only necessary if a female has placed her tunnel in an area where contact with humans is very likely.  

 

 

Pseudoscorpions are small arthropods (smaller than a pencil eraser) that have big scorpion-like claws.  However, pseudoscorpions are not poisonous and are completely harmless.  Most people find them in the bathroom, often in the sink or tub because the pseudoscorpions need water to survive.  Pseudoscorpions live outside under logs and in leaf litter.  Pseudoscorpions are predaceous and eat other small insects and mites.  Pseudoscorpions are harmless to humans and any found indoors can be carefully put back outside. 

This week there have been numerous calls about earwigs.  For some reason this seems to be a good spring for these insects.  Earwigs are common in gardens, but usually they go completely unnoticed.  They will also occasionally wander into homes.  Many people are disturbed by earwigs because they look very ferocious with large pinchers at the end of their abdomens.  They use the pinchers to intimidate, but it is definitely a case of the bark being worse than the bite.  They cannot pinch hard enough to even break skin.  Earwigs prefer to live in moist areas under logs or leaf litter.  Any earwigs found indoors can be swept up or you can return it to you garden. 

This past week we received two samples of viburnum leaves with wrinkled, reddened leaves.  Close inspection under a microscope revealed that the culprit was an eriophyid mite.  Eriophyid mites are common on many different plant species; however each species of eriophyid tends to feed on only a few closely related plant species.  Feeding by eriophyid mites can cause plants to form galls.  In the case of viburnum the feeding by the mites causes the plants to produce erineum galls – basically a patch of leaf hairs.  Within the patches of hairs are many thousands of eriophyid mites feeding on the plant.  Although the galls can make the plant unsightly, they usually do not cause the plant harm.  

Mosquito control in a yard situation is difficult and the best way to prevent mosquito bites is to use an insect repellant containing DEET.  There are a few things that you can do to reduce mosquito numbers in your yard. Make sure there is no standing water in your yard, mosquito larvae can develop in very small amounts of water.  Bird baths should have their water replaced every week to kill mosquito larvae.  Spraying bushes and other vegetation with insecticides may reduce the number of some mosquito species for a few days, but does not reduce the number of Culex mosquitoes (Culex mosquitoes are the primary vectors of West Nile Virus). 

There are three common ticks in Iowa; the Lone star tick, the American dog tick, and the black-legged tick (deer tick).   When walking in areas likely to contain ticks (woods, tall grass), the best way to avoid the ticks is to tuck your pant legs into your socks and spray around your ankles and on your shoes with an insect repellant.  When returning indoors you should remove and launder your clothing and inspect your body for any ticks.  Any ticks found attached to your skin should be pulled straight out with tweezers.  

The past few weeks we have received several larder beetle samples.  The larder beetle is a very common and widespread household insect pest.  The insect's name comes from it's presence in dried, cured meats stored at room temperature prior to refrigeration.  Today, larder beetles may be a pest in stored foods and other items of high protein content.  Larder beetles outdoors are valuable “recyclers” that play an important role in the breakdown and recycling of animal protein.

The larder beetle adult is slightly longer than 1/4th inch.  It is roundly oval and dark brown to black with a characteristic light colored band running across the body.   This light band contains 6 more or less prominent dark spots.  Larder beetle larvae are up to 1/2 inch long.  They are tapered in shape and covered with sparse, stiff hair.   There are 2 upward curved spines on the posterior end. 

Both the larvae and adults feed on items such as fur, hair, hides, feathers, and occasionally stored products such as dried fish, pet food and cheese.  In the house, however, the most likely source is dead insects or other animals (multicolored Asian lady beetles, boxelder bugs, attic flies, mice, etc.) that have accumulated inside walls or attics.

If a source of larder beetles can be determined than control can be achieved by discarding or cleaning infested woolens, feathers, furs, hides and so forth.  However, in the more typical, general infestation the source is probably the dead insects within the innerwall spaces and removal or sanitation is not practical.  In most cases only a few larder beetles wander into the house so no control measures need to be taken.  However if many larder beetles are entering the house from the walls it is advised to vacuum the areas and apply a residual indoor insecticide to room edges were the larder beetles are being found.