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Eddy County


Eddy Co. Invasionof the Insects Submitted by Dr. Jane Pierce Homeowners, gardeners and farmers are wondering what is behind the invasion of bugs this year. In Carlsbad, high temperatures, low relative humidityand a lack of good habitat often keep populations of many insects low. Dessication often results in over 60% mortality. This year higher rainfall and relative humidity increased egg hatch and subsequent survival of many insects, both pests and beneficial.Some have caught the attention of the public as well as gardeners and farmers. White lined sphinx moth caterpillars have been repeatedly mentioned in Facebook posts and calls to extension offices. High weed growth is behind these much larger than normal populations of these sphinx moths. As larvae they can feed on some garden plants, but in Eddy Co they seem to be content feeding on weeds. Adult white-lined sphinx moths are now commonly seen in area gardens and resemble hummingbirds while feeding on nectar.Alfalfa caterpillars and yellow striped armyworm have been more common than usual. Alfalfa caterpillars are found exclusivelyin alfalfa hay. Populations seem to be decreasing recently. Yellow striped armyworm populations have been building up on weeds and are still being found in high numbers. Because they feed on a wide variety of hosts they are not selected for insecticide resistance so they should be susceptible to control with most insecticides if they move to agronomic crops or gardens. However, as always, control is easier on younger larvae, and control with Bt products will only be effective in younger larvae. Large black beetles over 1 inch long have been particularly noticeable in this year in backyards, gardens and farms. Some have even made their way into buildings. Many homeowners have tried to control these beetles, assuming they are pests. In fact, most ofthese larger beetles are beneficial. Beetles represent about 25% of all described species of animals, with about 10% of all beetles (30,000 species) in the US alone. The number and diversity of beetles prompted a Haldane a British biologist to famously observe that God has “an inordinate fondness for beetles”. Many of these larger black beetles in Eddy Co are carabids, some of the most beneficial beetles. They are also called ground beetles and some common ones, called caterpillar hunters are voracious predators, particularly as larvae. They consume a wide varietyof insects including corn earworm and cutworms, consuming their body weight in insects every day. The last year they were this numerous was in 2010 during a large outbreak of cutworm in Eddy Co. hay fields. Although they are predators, many species of ground beetles also feed on weed seeds, making them beneficial in numerous ways. Unlike the larvae and many other beetles, and contrary to their name, ground beetle adults often climb plants in search of seed, prey or a mate. We have frequently seen them climbing weeds and cotton plants. Their ability to climb is part ofwhy they are often cited as significant predators in forest systems. Not surprisingly there are more than a few species in NM since the carabidae is one of the largest families of beetles, with 2,600 species in the US. Another group of large black beetles that are particularly common this year belong to the darkling beetle family. The large ones that are evident are scavengers unlike ground beetles. Although some darkling beetles and ground beetles can look very similar, darkling beetles have antennae with beadlike segments and mouthparts that are not easily visible from above. Most of the darkling and ground beetles we are seeing prefer to feed at night, but some are active during the day, particularly some of the more brightly colored beetles that can reflect sunlight. They are often common but not as noticeable as their nocturnal cousins this year. Although it is understandable that homeowners don’t want their home invaded, please consider leaving ground beetles, in particular, alone when they are outside as they are working to keep populations of insect pests in check. is a research/extension entomologist with New Mexico State University.

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