Q. This is a photo of a caterpillar that is on most of the plants in our neighborhood. Do you know what it is and what we can use to get rid of them? Caterpillar explosion in the desert after a rain. This probably the caterpillar or larva form of a sphinx moth. A. A caterpillar explosion, just like in the picture, has occurred all through Las Vegas and Arizona where it’s been raining and, because of the water, food supply is abundant. Caterpillars like these can be a common sight where there are so-called “summer monsoons” and rains such as found in central and southern Arizona and this year as far north as Las Vegas. Southern Arizona (Sonoran desert) gets more than double the water than the Mojave desert so there is a lot more food to sustain “caterpillars”. https://dbg.org/yellow-hornworms-invade-phoenix/ https://www.usatoday.com/story/news/nation/2014/09/24/monsoon-season-leaves-arizona-crawling-with-caterpillars/16186181/             They should be easy to control with soap and water sprays, Neem oil as well as any commercial pesticide available such as Sevin. It’s important to follow any label directions present for the right dosage and spray these immature insects. After they die from any kind of pesticide, then there’s always the cleanup.             However, this year’s “hatch” has been particularly large in southern Nevada compared with previous years. Two years ago in Tucson, Arizona, the hatch was a large one due to summer monsoons like we had in Las Vegas. The conditions must be perfect; several large rains following each other which cause plants to grow and provide food and coverage. Sometimes this food might be our vegetables, landscape plants, and fruit trees. Sometimes this food is found only in the desert.             These caterpillars are usually the white-lined sphinx moth (hummingbird moth) painted in a lime green or yellow with black longitudinal stripes, with or without a spine on the end. These insects sometimes act as pollinators just like butterflies, flies and other flower loving insects. After they have gained the right size, they drop to the ground and develop into the sphinx moth in moist soil. On the negative side we might see a burst of pest problems in our tomatoes and grapes due to their munching. So be prepared!