6/9/17 Caterpillar Update
WINTER MOTH CATERPILLAR
Winter moth caterpillars have finished feeding and have pupated. Damage from this year’s caterpillars appears to be significantly down in most areas. A probable reason for the 2017 reduced number of winter moth caterpillars can be traced back to the cold, freezing weather the first few days of April 2016, just as the winter moth eggs began to hatch.
GYPSY MOTH CATERPILLARS
Gypsy moth caterpillars remain numerous and were observed in 3rd and mostly 4th instars. They were found feeding on a wide range of plant material (apples, crabapples, maples, Fothergilla, Hamamelis, etc), but the largest numbers were found feeding heavily on oak. They were also found feeding on plants, like small white pines, in the understory of oak. According to staff from Dr. Joe Elkinton’s UMass lab, many understory small pines in Wompatuck State Park, Hingham, MA, have been completely defoliated. Gypsy moth frass (feces) can be heard dropping through the trees as they feed. This sound will continue as the gypsy moth caterpillars continue to feed and grow larger over the next few weeks. owever, there may be some relief. The cool, wet weather has been conducive to the caterpillar-killing fungus, Entomophaga maimaiga, and many dead, fungus-killed caterpillars were seen hanging down on oak and pine foliage; staff from Dr. Elkinton’s lab are predicting that these numbers will increase.
5/26/17 Gypsy Moth Update
Winter moth caterpillars remain active, although in low numbers in many areas, and are in 3rd and 4th instars. Also, in many areas, damage to foliage from winter moth caterpillar feeding is greatly reduced from previous years. Continue to monitor high value trees and shrubs and manage, if found. Gypsy moth caterpillars are small, mostly 2nd and 3rdinstars and are active on a wide variety of plant material including Fothergilla, blueberries, roses, crabapples and apples, along with the usual hosts of oak, maple, etc. Manage early, while caterpillars are small and before damage is significant.
Roseslug sawfly is now active on roses. Monitor rose foliage for the small, slug-like, pale-green larvae, if left untreated, the sawfly larvae will skeletonize the rose foliage and the foliage will appear ‘burned’, resembling tan lace. Bt (Bacillus thuringiensis) is not effective on sawfly larvae, although insecticidal soap and products containing Spinosad are. Like most insecticides, do not apply Spinosad to plants that are in bloom, to avoid harming pollinators. Azalea sawfly larvae are now active on deciduous azaleas like Exbury azaleas. The small, bright glossy green caterpillar-like larvae are difficult to see and can often be found feeding on the outer margin of a leaf, feeding inward, leaving only the midvein; manage early to avoid defoliation.
Monitor the tips of Euonymus branches for webbing of the Euonymus caterpillar. The caterpillars feed and web the leaf tips together.
5/12/17 Gypsy Moth Update
The gypsy moth caterpillar dispersal (ballooning) is well under way in most locations where this insect has been recently problematic in Massachusetts. Tiny caterpillars have been observed to be settled on young oak foliage and actively feeding in certain locations. Dispersing caterpillars were observed in Hanson, MA on 4/29/17, crawling away from their egg masses and suspected ballooning was reported in that location on 5/2/17. Dispersed caterpillars were observed on newly opened oak leaves on 5/3/17 at a site in Belchertown, MA. Ballooning caterpillars were observed in Monson, MA at a specific location in very high numbers, as reported with photographic evidence from a homeowner on 5/4/2017. Gypsy moth egg hatch was confirmed in Milton, MA on 5/6/17 and ballooning caterpillars were reported on that date in Ware, MA. Previous locations where gypsy moth egg hatch has been reported during the past 2-3 weeks include (but are not limited to) Belchertown, Dennis, Hanson, Hingham, Petersham, Randolph, Sandwich, Sturbridge, and near the Wachusett Reservoir. At a site in Belchertown where egg hatch was first observed on 4/26/2017, egg masses observed hatching on that date were devoid of newly hatched caterpillars (on top of the masses) by the time they were re-visited on 5/3/17. Egg masses observed with hatched caterpillars resting on top of them on 5/3 were devoid of caterpillars when they were re-visited on 5/10/17. It would appear, at least at the site being monitored in Belchertown, that the egg masses have hatched over an extended period of time and that ballooning has occurred throughout that period as caterpillars were observed to be feeding on oak and maple in that area. It would appear that hatch and dispersal is mostly over and that by the next Landscape Message, most of the young gypsy moth caterpillars, in the areas of the state where they are problematic, will have settled to feed. (Many are actively feeding at this time. If you find a host plant leaf with small, tattered holes in it, flip the leaf over and you may find a small, roughly ¼ -inch long gypsy moth caterpillar feeding on the leaf underside. The size of the caterpillars in your area depend on when hatch began. These caterpillars are dark in color, hairy, but at this time the blue and red raised “wart-like” spots on the back are not yet as apparent as they will be in the older caterpillars.)
5/5/17 Gypsy Moth Update
In Hingham MA, Gypsy moth began to hatch around April 26 and in Hanson around April 29, and hatch continues in each of those areas. The earlier hatched gypsy moth caterpillars have started to balloon (spin silk and float through the air) and have settled in to feed. However, with the incredible number of gypsy moth caterpillars out there that have just hatched, or are about to hatch, we should see ballooning increase this coming week. The small black caterpillars are covered with tiny hairs which are capable of causing an allergic skin reaction or rash for some people. In past years, many people reported contracting a skin rash after the gypsy moth caterpillars landed on bare skin. Examining oak buds and newly expanded oak leaves revealed both gypsy moth caterpillars and winter moth caterpillars; however, the gypsy moth caterpillars greatly outnumbered the winter moth caterpillars. Gypsy moth caterpillars were also found on blueberry flowers and buds, European beech, maples etc. Winter moth caterpillars and gypsy moth caterpillars are small right now, and damage is not yet significant. However, as the caterpillars feed, they will continue to grow in size. So, continue to monitor host trees and smaller plants, and if these caterpillars are found, manage them while they are small before too much damage is done. (See Tawny Simisky’s Insect section of the Landscape Message).